Social Inequality

Long-Term Trends and Their Relationships with Happiness, Homicide Rates and Life Expectancy

Chengyu Wu, Tian Xu, Xinhui Liu, Yunzhen Jin

Dr.Sabine Hoffmann, Mona Niethammer, Lona Koers, Marie Scherzer

2025-12-18

Agenda

  1. Overview and Terminology

  2. Research Questions

    • How has social inequality evolved over time?
    • How much do countries differ when it comes to social inequality?
    • What is the relationship between social inequality and other factors?
  3. Summary and Limitations

Overview

Data Preparing

  • Data Cleaning

    • Do not interpolate missing data
    • Use available data points
    • Show real data
  • Data Filtering

    1. Time
      Inequality over time (2000-2023)
      Differences across countries(2022)
      Inequality and its associated factors(2021)
    2. Country
  • Weighting

Terminology

  • Gini Coefficient1

    • Most widely used measure of income inequality
    • Range: 0 = perfect equality, 1 = extreme inequality
  • Before-tax Income1

    • Income received before taxes or government transfers
    • Reflects market-based income distribution
  • After-tax Income1

    • Income after subtracting taxes and adding government transfers
    • Indicates resources actually available to households

Source:[1] World Bank Poverty and Inequality Platform

Agenda

1. Overview and Terminology

  1. Research Questions

    How has social inequality evolved over time?
    How much do countries differ when it comes to social inequality?
    What is the relationship between social inequality and other factors?

3. Summary and Limitations

Agenda

1. Overview and Terminology

  1. Research Questions

    How has social inequality evolved over time?
    How much do countries differ when it comes to social inequality?
    What is the relationship between social inequality and other factors?

3. Summary and Limitations

Countries Difference

Agenda

1. Overview and Terminology

  1. Research Questions

    How has social inequality evolved over time?
    How much do countries differ when it comes to social inequality?
    What is the relationship between social inequality and other factors?

3. Summary and Limitations

Indicators

Indicator Concept Unit
Happiness Self-reported life satisfaction 0-10 scale

Happiness

Indicators

Indicator Concept Unit
Happiness Self-reported life satisfaction 0-10 scale
Homicide rate1 Number of deaths from homicide per 100,000 people rate per 100,000

Source:[1] WHO Mortality Database

Homicide Rate

Indicators

Indicator Concept Unit
Happiness Self-reported life satisfaction 0-10 scale
Homicide rate Number of deaths from homicide per 100,000 people rate per 100,000
Life expectancy average years that newborn is expected to live year

Life Expectancy

Agenda

1. Overview and Terminology

2. Research Questions

How has social inequality evolved over time?
How much do countries differ when it comes to social inequality?
What is the relationship between social inequality and other factors?

  1. Summary and Limitations

Summary

Social Inequality

  1. Global trend
    • Downward trend
    • Consistently high level
  2. Cross-country difference
    • Large difference across countries
  3. Higher Gini linked to:
    • Lower happiness
    • Higher homicide rate
    • Lower life expectancy

Limitations

  • Data Quality

    • Data gaps
    • Subjective indicators bias
  • Research Design

    • Single measure inequality indicator
    • Cross-sectional data

Reference

- Joe Hasell (2023) - "Measuring inequality: what is the Gini coefficient?" Published online at OurWorldinData.org. Retrieved from: 'https://archive.ourworldindata.org/20251209-133038/what-is-the-gini-coefficient.html' [Online Resource] (archived on December 9, 2025).
- Joe Hasell, Bertha Rohenkohl, Pablo Arriagada, Esteban Ortiz-Ospina, and Max Roser (2023) - "Economic Inequality" Published online at OurWorldinData.org. Retrieved from: 'https://ourworldindata.org/economic-inequality' [Online Resource]
- Bastian Herre, Fiona Spooner, and Max Roser (2013) - "Homicides" Published online at OurWorldinData.org. Retrieved from: 'https://ourworldindata.org/homicides' [Online Resource]
- Bastian Herre and Fiona Spooner (2023) - "Homicide data: how sources differ and when to use which one" Published online at OurWorldinData.org. Retrieved from: 'https://archive.ourworldindata.org/20251125-173858/homicide-data-how-sources-differ-and-when-to-use-which-one.html' [Online Resource] (archived on November 25, 2025)
- Esteban Ortiz-Ospina and Max Roser (2017) - "Happiness and Life Satisfaction" Published online at OurWorldinData.org. Retrieved from: 'https://ourworldindata.org/happiness-and-life-satisfaction' [Online Resource]
- Saloni Dattani, Lucas Rodes-Guirao, Hannah Ritchie, Esteban Ortiz-Ospina, and Max Roser (2023) - "Life Expectancy" Published online at OurWorldinData.org. Retrieved from: 'https://ourworldindata.org/life-expectancy' [Online Resource]